This chapter deals with principles of warfare.
Do not fear as you prepare to go to battle – When Israel would face opposing armies possessing horses, chariots, and people which would far outnumber their own, God’s message to His people was do not be afraid, do not tremble, and do not let your heart faint (20:1-3). Why would there be no need to fear their enemies? Because the Lord would go with them, fight for them, and save them (20:4). The Israelites were not to sit on the sidelines and do nothing, though. They had to engage the enemy, use their weapons, and finish the fight. We, too, can take comfort in knowing that our Father will bless us as we engage in spiritual warfare and use His armor (Ephesians 6:10-17).
Some soldiers allowed to return home – In what instances would an Israelite soldier be exempt temporarily from military duty? (1) If he had built a new house but had not dedicated it (20:5); (2) If he had planted a vineyard but had not yet eaten its grapes (20:6); (3) If he had betrothed a woman but had not yet married her (20:7); (4) If he was “fearful and fainthearted” (20:8). This last one was the most serious scenario. A soldier who was afraid could cause his fellow soldiers to fear and lose heart, and that would be disastrous. This reminds us of the instance when 22,000 of Gideon’s soldiers returned home out of fear (Judges 7:3). As soldiers in the Christ’s spiritual army, He does not want us to have a spirit of fear (2 Timothy 1:7). Fear paralyzes and hinders.
Pursue peace before taking destructive action – As the army of Israel approached a city, they first were to make an offer of peace. If the people accepted the peace accord, then they would become the servants of Israel, but their lives would be spared (20:10,11). If, however, it refused Israel’s peace offer, then Israel was to besiege the city and kill the males. The women and little kids were to be spared (20:13,14).
The above-noted instructions applied only in those cases that did not involve the cities and people of the land of Canaan (20:15). For the Canaanites, it was a different story. How was Israel to deal with the Canaanite cities? No peace was to be offered. Instead, Israel was told to destroy them completely (20:16,17). Why? “Lest they teach you to do according to all their abominations which they have done for their gods, and you sin against the LORD your God” (20:18). Thus, it is clear that there was a spiritual motive behind God’s “wipe-them-out” clause. When you think about it, every single instruction that the Lord has given throughout history always has been with man’s spiritual well- being in mind.
— Roger D. Campbell